Distillation of fatty acids



y 8, 194.0. M. H. ITTNER 2,202,007

DISTILLATION 0F FATTY ACIDS Filed-June 11, 1 956 a Sheets-Sheet 1 TOVACUUM ZNVENTOR BY M v dwnwq ATTORNEYS May 28, 1940, M. H; ITTNER2,202,007

' DISTILLATION 0F FATTY ACIDS F iled June 11, 1936 s Sheets-Sheet 2 TOVACUUM 7/ INVENTOR uzq" W M BY 22.2% flaw/M ATTORNEYS May 28, 1940. M.H. ITTNER DISTILLATION OF FATTY ACIDS Filed June 11; 1936 3 Sheets-Sheet5 INVNTOR BY 1 Mi -41 ATTQRNEYS mw W I! h, 255 v NW hm MW .ww MEJJFQQPatented Ma 28, 1940 UNITED STATES PATENT OFFICE 2,202,007 DlSTlLLATIONF FATTY Aoms Martin Hill Ittner, Jersey City, N. J., assignor toColgate-Palmolive-Peet Company, Jersey City, N. J., a corporation ofDelaware Application June 11, 1936, Serial No. 84,626

Claims.

a radically smaller heat consumption than has heretofore been possible,while at the same time the quality of the fattyacids distilled isimproved, and the losses in distillation, due to the formation of tarsand to decomposition, are substantially lessened.

The process of the present invention, while adapted for, and useful for,the distillation of high boiling liquids generally, particularly suchhigh boiling liquids as are not miscible with water and areadvantageously distilled by a vacuumsteam process, such as high boilingpetroleum fractions, is particularly adapted for, and particularlydesigned for, the distillation of fatty acids.

The term fatty acids, as used herein, and as commonly used in industry,includes not only the true fatty acids, which are saturated, but alsothe related unsaturated acids with varying degrees of unsaturation.These fatty acids are commonly obtained by the saponification of naturalfats and oils; which consist of triglycerides of the fatty acids, andare generally obtained as mixtures of various saturated fatty acids andvarious unsaturated fatty acids. In general, the saturated fatty acidsare more stable than the unsaturated fatty acids, and are more resistantto decomposition by heat and to oxidation.

The improved process of the present invention makes it possible todistill fatty acids with a radically loweredheat consumption because itpermits the recovery of the heat from condensation of the fatty acidvapors as well as sensible heat of the fatty acid vapors and the hotcondensed fatty acids, and, where jet steam is used to aid in thedistillation, much of the sensible heat of the water vapor, and theutilization of such heat for preheating the fatty acids'and producingthe jet steam used in the distillation, and also increases the economyof the operation by decreasing the losses due to decomposition and tarformation. This process permits the use of much higher vacua, or lowerabsolute pressures, within the still and in the vapor space over theliquid being distilled and thereby reduces the amount of jet steamrequired to aid in the distillation and also lowers the temperature atwhich the distillation may be carried out in a' commercial manner.

Apparatus as a whole advantageously adapted for use in carrying out theprocess includes a heating zone, in which the fatty acids beingdistilled are heated and in which the volatilization takes place, avapor space above the heating zone, a separator, in which the vapors areseparated from entrained material and a suitable cooling zone, in whichthe fatty acid vapors are condensed and the accompanying water vaporscooled, all

within a single air-tight shell similar to the shells of stills nowcommonly provided. The apparatus is also provided with suitable meansfor supplying heat to the material being distilled, such as highpressure steam coils, and with ejector jets for mixing the contents ofthe still with superheated steam if desired, the jets being so locatedas to insure effective and uniform heating of the still contents by theheating coils; suitable insulating means for preventing the passage ofheat from the separating zone, through which the vapors pass directlyfrom the vapor space above thestill contents, to the cooling zone, orzones, which is or are annular and surrounding the separator, theinsulating device advantageously defining the separator; and a suitableconnection to a vacuum device to permit the flow of water vapor from thestill and to insure the maintenance of a low pressure in the still.

The improved process of the invention in its so that the heat fromcondensation of the fatty acids, and a large part of the sensible heatof the fatty acid vapors and the hot condensed fatty acids and a largepart of the sensible heat of the water vapor is used to preheat thefatty acids fed to the still, and to generate and superheat thesuperheated steam used as jet steam in the still. Thus by the process ofthe present invention, a very large part of the available heat of thevapors is recovered and used, and the only heat which it is necessaryfor the high pressure steam to supply is the latent heat of vaporizationof the fatty acids, and the heat lost by radiation from the heating zoneof the still.

In the apparatus, all passages through which the vapors must pass, thatis, the vapor space above the still contents, the separator, and thecooling zone or zones are of such substantial size that very littleresistance to flow of the vapors is offered, and the pressure differencebetween different parts of the still is very slight, a pressuredifference as small as a fraction of a millimeter of mercury between thevapor space just above the still contents and the vacuum device outsideof the still used to maintain the vacuum within the still being easilyobtainable. Because of this small pressure drop, the apparatus may beoperated, and the process carried out, while pressures as low as threemillimeters of mercury are maintained within the still while using openjet steam. The low pressure which may be maintained within the still isdistinctly advantageous, as it greatly decreases the temperature atwhich effective and rapid distillation of the fatty acids can takeplace, and thus reduces to a substantial extent the decomposition andtar formation which ordinarily occurs.

The invention will be further illustrated and explained in connectionwith the accompanying drawings, which show, in a diagrammatic fashion,

apparatus which is adapted for carrying out the process of theinvention, but the invention is not limited thereto.

In the drawings:

Fig. 1 is a vertical section, with parts in elevation, of a suitablestill;

Fig. 2 is an elevation showing a suitable arrangement of the variousparts of the apparatus;

Fig. 3 is an enlarged section of a suitable device for drawing fattyacids from the still;

Fig. 4 is a vertical section of a portion of a still, showing a modifiedarrangement of the cooling zones; and

Fig. 5 is a horizontal section Fig. 4.

In Fig. 1 the still I is shown. as provided with an outer shell 2, witha lining 3" of a suitable corrosion-resistant metal, such as stainlesssteel, attached thereto. The shell is advantageously made in threesections, 2a, 2b, and 2c, bolted together by flanges 4. The interior ofthe still is divided into several zones or sections in which theoperations of the process take place. At the bottom of the still areprovided coils 5 which may I be provided with high pressure steam, orother suitable heating medium, to provide the heat necessary for thevolatilization of the fatty acids.

The level of the liquid being distilled is normally maintained somewhatabove the heating coils. Above the heating coils, and above the liquid,is a vapor space 6 leading directly into the separating zone 1, which isof large diameter and is provided with the helical or spiral fins 8. Thevapor space and the separator are defined by the double-walled partition9 which is advantageously made of relatively thin metal and withpolished surfaces. Small holes l0 are provided in the outer sheet ofthis insulating partition to provide communication between the still andthe interior of the partition so that the same pressure exists withinthe partition as exists within the still proper, these holescommunicating with a relatively cool portion of the still, sothat nocondensible vapors, which might condense between the walls of thepartition, and impair its insulating efficiency, can enter through theminto the space between the walls and condense. This partition rests uponthe lipped ledge II, which provides a small ledge in which liquid fattyacids collect and form a liquid seal to prevent the transfer of vaporsbetween the still wall and the insulating partition. A few small holes i2 may be provided at the bottom of the inner wall of this partition topermit the drainage of any maof the still or terial which may get withinthe partition. The level of the liquid being distilled is normallymaintained a little above the ledge ii. A gauge glass i3 is provided todetermine the level of the liquid.

The insulating partition defines the separating zone, which is of adiameter approximately onehalf the diameter of the shell, and below theseparating zone flares out to the diameter a little less than that ofthe shell, as shown at l4, forming the vapor space above the liquid, andproviding a throat leading the vapors into the separating zone, thusserving not only to insulate the sides of the separating zone, but alsoto insulate the vapor space and prevent or minimize losses of heatthrough the sides of the still adjacent to the vapor space. Above andsurrounding the upper portion of this insulating partition is abell-shaped partition l5 which is double-walled, and which serves todeflect the vapors which pass upwardly through the separating zone downpast the series of coils I6, I! and I8, which constitute the primarycooling agencies, where the vapors are cooled and a large proportion ofthe fatty acids condensed. This bell-shaped deflector is supported onbrackets i9, and the vapors after passing down between this bell and theinsulating partition pass up between the bell and the wall of the still,past the coils 20 and 2| and then pass out through the pipe 22 to asuitable vacuum device.

The deflector bell is advantageously doublewalled, and is made of asuitable corrosion-resistgutters 24 at the top, and the upper sectionconsisting of an inner and an outer dome 25, which rest in the guttersand are held in place by bolts 26. Suitable holes are provided in thebell-deflector for the passage of various tubes leading to the coilswhich are placed between the insulating partition and thebell-deflector.

Three sets of coils I6, I1 and I8 are provided between the partition andthe bell-deflector. Of these, the upper section 16, with an inlet 21 isused forsuper-heating the steam. The steam passes through this coilwhere it is superheated and then passes down the inner pipe 28 of thedouble pipe 29 provided in the center of the coil and passes out of thispipe through the jets 30, which are preferably arranged so that thedischarging steam and the fatty acids which are intimately admixed withit in the jets have a horizontal path, and are forced into intimatecontact with the heating pipes 5 thus insuring the uniform and effectiveheating of the liquid, and its intimate admixture with the superheatedjet steam.

The second set of coils l1 leads from the manifold 3| into which thefatty acids to be distilled are introduced through inlet 32 to themanifold 33, and thence to the outer pipe of the double pipe 29 whichruns down the center of the still and discharges the heated fatty acidsinto the liquid at the bottom of the stillsomewhat below the uppersurface.

The third set of coils I8 leads from the manifold 34 to the manifold 35and these coils are used to vaporize the water and form the steam whichis subsequently superheated and used as jet steam in the distillation,water being introduced through inlet 36, and hot water and steam beingtaken from outlet 31. The vapors thus pass over the three sets of coilsin series, superheating the steam, preheating the fatty acids, andproducing the, steam which is used in the distillation. These coilsare-so arranged that any fatty acids which may be deposited upon them byof the still down into the trough. Between the bell-deflector and theouter wall or shell of the still there are provided cooling coils 20 and2H, through which cold water or other cooling agent may be circulated tofurther cool the vapors after they have been partially cooled by 'theother coils, and thus to condense the last traces of fatty acid and toinsure that the vapors which pass out of the still are substantiallyfree from fatty acids. In the apparatus illustrated, two such coolingcoils are provided; but one cooling coil may .be used if desired, ormore than two cooling coils may be used.

An outlet 4| is provided at the side of the still from the trough forthe removal of the fatty various sizes, and with wide variations in theproportions of the various zones and parts of the apparatus. 2400 poundsof fatty acids per hour, a still having an-outer shell about 8 feet indiameter may be provided, which may be about 15 feet high. Theseparating zone, which should be quite large. may be about 4 feet indiameter and about 6 feet high, the vapor space beneath the separatormay be about 3 feet high, with the heating zone where the liquid fattyacids are heated being about 3 feet deep. The deflector-bell may beabout '7 feet in diameter and about 7 feet high. A still of suchdimensions provides adequately large vapor spaces or passages whichoffer no substantial resistance to the vapor flow. The cooling coils,and the heating coils, may be made of 2 inch tubing, ofa suitablecorrosion-resistant metal.

Fig. 2 is a diagrammatic sketch of the exterior of the still, showingthe general arrangement of the exterior parts. shown at I with theheating coils connected, by pipes 43a provided with valves 43b, to asuitable manifold 43 connected to a high pressure steam supply to supplythe steam required for heating,

I brought into pipe 45 from an outside source, the

flow being controlled by the needle valve 41. Distilled water ispreferably used. The water flows through the tube 46 and connection 36and mamfold 34 into the coils, where a part of it becomes For a stilldesigned to distill about In this figure, the still is.

converted into steam by the heat absorbed from the fatty acid vaporswhich flow over the coils and the heated cooling water and the steamgenerated rise through the coil and flow out through the connection 31and tube. 48. Most of the water returns to tube 46 through connection50, while the steam and the rest of the water go into separator 49, inwhich the water may return to tube 46 through connection 5!. The levelof thewater in the separator is maintained a little below tube 48 at thelevel of outlet 54, and is indicated by the gauge glass 52.

A suitable connection 53 is provided at the top of the separator forsupplying steam'from an outside source when starting operation, and witha suitable pressure relief valve 54 for the discharge of excess steamand water. Another pressure relief valve 55 may be provided at the topof the separator. A pressure gauge '56 may be provided at the top of theseparator to show the pressure maintained within the chamber. Thechamber is preferably maintained at a superatmospheric pressure, e. g.,5 pounds gauge or less, to avoid the possibility of air leaking intothe, separator and into the still. At the top of the separator isprovided an outlet 51 for the separated steam which is connected to tube58 which leads through connection 2'! to the superheater coil by theparallel tubes 59, each provided with a valve 60, and with an orifice Blwhich may be of the same size or of different sizes, and which enablethe flow of steam from the separator to the superheater coil to beadjusted to a predetermined, desired amount.

The cooling coils 2B and 2!, between the belldeflector and the outerwall of the still may be supplied with cold water through inlets 62 and63 and may discharge through outlets 64 and 65, the cold water thusflowing concurrently with the outgoing vapors, or the direction may bereversed.

In Fig. 3 is illustrated a suitable connection for the removal of liquidcondensed fatty acid from the trough 38. (Fig. 1). As illustrated, abushing 66 is welded into the lower part of the dam 39 of the trough,and a special nipple 61 is provided to be screwed into this bushing. Aflanged nipple 68 with an inner diameter somewhat greater than the outerdiameter of nipple .57 iswelded to the shell, so that the nipple 61 whenconnected to the bushing 66 is centrally located within the flangednipple 68. Radially slotted bolt holes are provided around the flange ofthe nipple 6B. The nipple 61 is threaded on each end with standardpipethreads' and along a portion of its outer surface with machinethreads having the same pitch as the pipe threads but having a largerouter diameter. A small recess is provided in the face of the flangednipple 68 for a gasket 59. A smooth-faced flange l0 provided-with radialslots corresponding to those in nipple 68 is provided with an inner holethreaded to match the machine threads on the nipple 61. Nipple 61 isthen screwed into bushing 66 and the flange screwed down until itpresses upon the gasket. The flanges are then bolted together with boltsH and tightened so as to make a tight joint between them. A follower 12is also screwed upon the outer part of nipple 51 with a grommet 13between it and the that air does not leak into the still at thesepoints.

In Figs. 4 and 5 there is illustrated the upper part of a still showinga modified arrangement of the cooling zone, with a modified vaporpassage, which may be used. In the modification of the apparatusillustrated in these figures, there is provided a separating zone 14,defined by an insulating partition 15 of the same construction as thatshown in Fig. 1, within which are the helical or spiral vanes 16, two innumber, which serve to remove entrained matter from the vapors. In thismodification, no deflector-bell is used, the vapors passing from the topof the separating zone and being deflected by the top of the still.Three sets of cooling coils, l1, l8 and 19, are provided in the zonebetween the insulating partition and the wall of the still, the vaporsafter being deflected from the top of the still passing over thesecoils. These coils are used for much the same purposes as those providedin the apparatus described in Fig. 1, the upper coil being used tosuperheat jet steam, the central coil to preheat fatty acids, and thelower coil to generate steam. There are also provided two helicalbaffles 80 and 80a having about the same pitch as the cooling coils andeach extending a little more than one-half of the Way around theinsulating partition 15, which deflect the vapors so that instead offlowing downwardly over the cooling coils, they flow downwardly andaround the insulating partition in a helical or spiral path,

finally passing out of the still through the opening 8| to the vacuumdevices.

In the arrangement shown in Figs. 4 and 5, care should be taken that thecooling coils have an adequatearea to cool the vapors to an extentsufficient in insure that-substantially all of the fatty acids arecondensed within the still, so that no substantial amount passes on tothe vacuum devices. The fatty acids condense on the cooling coils, anddrop down into a collecting trough, which is of the same construction asshown in Fig. 1.

In the arrangement shown in these figures, instead of a singlesuperheating coil being used, a plurality of coils is provided, thesaturated steam entering through inlet ,82, into manifold 83 passingthrough the coils H to be superheated and into manifold 84 and then intothe inner pipe 85 of double pipe 86 and to the jets. The fatty acidsenter the coils 18 through inlet 88 and manifold 89, and pass spirallyupward through the coils into manifold 90 and.then pass into the outerpipe of the central double pipe. Cooling water is supplied through inlet9| to manifold 92 from where it passes spirally upward throughcoils 19into manifold 93 and then passes into a separator such as described inconnection with Fig. 2 through outlet 94.

In the apparatus illustrated in Fig. 1, no insulation is provided on thestill. It will be understood that insulation is provided at the lowerpart of the still, that is, around the portion of the still where theliquid material is maintained and somewhat up the sides of the still atthe vapor space. It is not necessary to provide much insulation at thelevel of the vapor space, as the insulating partition effectively servesto insulate this portion of the still and to prevent any substantialloss of heat by radiation. 'Above the vapor space, no exteriorinsulation need be provided, and in fact, such insulation is generallyundesirable. At this portion of the still, it is desirable to cool thevapors, and provision is even made for the introduction of cold water toprovide for the complete cooling of the vapors. The walls of the stillabove the vapor space normally are quite cool, and, in any case, anyheat which might be lost by radiation from these portions of the stilldoes not rob heat from the heating zone, and does not lessen the thermalefiiciency of the still but may add to its condensing efficiency.

In operating the still illustrated in Fig. 1, a body of liquid fattyacids is maintained in the bottom of the still at a level somewhat abovethe top of the heating coils, and is heated by the high pressure steamin the coils. A high vacuum is produced in the still by a suitablevacuum device (not shown). superheated jet steam is introduced throughthe jets into the liquid material, insuring the intimate contact of theliquid material with the heating coils and insuring the effective anduniform heating of'the material. The vapors of the fatty acids, admixedwith the water vapor, pass up from the liquid material into the vaporspace 6 and then through the throat into the separating zone i. Here thevapors are deflected by the helical vanes 8. The attenuated fatty acidvapors and water vapor are defiected readily by the vanes, and nosubstantial resistance to the flow of these vapors through theseparating zone is offered. Any entrained liquid or non-voiatilizedmaterial which is carried along with the vapors through the vapor spaceinto the separating zone, being many times heavier than the vapors, isnot diverted from its path and comes into contact either with the vanesof the separator or the insulating partition and flows down and dripsback into the liquid in the bottom of the still. Any material which isso deposited on the vanes will flow downward along the line of greatestslope, which is toward the center and down the center of the vanes. Thisseparator may be provided with any suitable number of vanes, four vanesbeing suitable, as the size of the passageway for the vapors is so greatthat no substantial resistance to their flow is offered. The vaporsafter passing up through the separating zone are deflected by thebell-deflector i5 and pass down over the three sets of coils betweenthis bell and the insulating partition 9. In the lower set of coils,cooling water enters through tube 36 into the manifold 34 and passesupwardly through the spiral coils into the upper manifold 35, a largepart of the water being converted into saturated steam, and the admixedwater and steam being separated by connection 50 and separator 49, thewater being returned to the coils and part of the steam being passedthrough one or the other, or both, of the orifices 6| in controlledamounts, and then passing through the upper coil IS in which it issuperheated. The saturated steam to be superheated thus comes intoindirect contact with the hottest fatty acid vapors coming from theseparating zone and is superheated to a temperature approximating thetemperature of the liquid material in the still. The steam after beingsuperheated passes from the coil downwardly through the inner pipe ofthe double pipe and is conducted by suitable connections to a pluralityof steam jets in the lower part of the still where it is discharged asjet steam to assist in the distillation.

The bell-deflector l5 serves not only to deflect the vapors downwardlyand over the cooling coils but also serves to prevent loss of heat fromthe vapors into the space abovethe bell-deflector and close to the topof the still. The vapors in this upper space are cool, and any heatsupplied to them from the hot vapors from the separating zone would, ofcourse, be wasted and lessen the efliciency of the condensation in thespace between the bell-deflector and the outer still shell. -Thedouble-walled deflector-bell, which is advantageously made of polishedmetal, and which is highly evacuated, being indirect communication withthe still, serves effectively as an insulating agent to prevent thetransfer of heat from the hot vapors to the cooler vapors above, so thatthe vapors which come into contact with the superheater coils, and withthe preheating coils, are substantially at the temperature of the liquidcontents of the still.

The fatty acids which are fed to the still are preheated, in the secondset of coils it by the fatty acid vapors and the water vapor thataccompanies them. The fatty acids, preferably dry, are introduced intothe coils it by the .tube

32 connecting with manifold 36 which distributes the fatty acids throughthe coils whence they pass spirally upward and discharge into themanifold 33. The fatty acids are thus preheated by heat exchange withcountercurrent flow of the the temperature or the fatty acid vapors toany substantial degree. The preheated fatty acids,

substantially at the temperature of the still con tents,'are led downbetween the inner pipe and 'the outer pipe of the double pipe to a pointbelow the level of the liquid in the heating zone and near its center.The amount of feed is regulated by the rate of distillation and is suchas to maintain the liquid level in thestill at its most eifective point,the gauge glass indicating this level.

The heat exchange-coils which condense fatty acids and cool the liquidcondensed fatty acids and cool the fatty acid vapors and the water vaporand generate and superheat thesteam used as jet steam and preheat thefatty acids fed to the still are so placed that none of the fatty acidswhich may condense on their surfaces may drop into the separating zoneand thence into the bottom of the still but all must run downwardbetweenthe insulating partition and the bell and be collected in thetrough. If desired, instead of collecting all of the condensed materialin a single collector, separate collectors may be placed at variouslocations within this cooling zone to permit fractionation or fractionalcondensation of the hot vapors. For example, if fractional condensationof hot fatty acid vapors is desired, or if the still is used for the distillation of high boiling petroleum fractions where fractionalcondensation is desired, the still may be provided with a series ofcollectors along the coolingzone, so that as the vapors becomeprogressively cooled, and as the condensate becomes more and morevolatile, the more volatile constituents may be separated from the lessvolatile constituents.

The preheating which takes place' After the vapors have passed downbetween the space between the insulating partition and thebell-deflector, they pass upwardly between the bell-deflector and thewall of the still, the supplementary cooling coils 20 and 2| beingprovided here to insure the complete condensation of fatty acid vaporsbefore removing the water vapor from the still through the upper outletwhich leads to the vacuum device.

Thus the fatty acids condense within the cooling zone with substantialcompleteness and run down into the collecting trough 38 from which theyare removed through the outlet M, which may be constructed as describedabove, by a pump or drop-leg or other suitable means.

The amount of heat which is available for accomplishing the preheatingoperation, when the still is properly constructed and the process isproperly carried out, is considerably in excess of that required. Thusin condensing the fatty acid vapors and in cooling the resulting liquidfatty acids and cooling the water vapor considerably more heat is givenoff than is necessary to generate and superheat the open jet steamemployed and to preheat the fatty acid feed. This excess .heat isabsorbed in part by the supplementary cooling coils located between thebell-deflector and the wall of the still and is partly radiated from theouter part of the shell. Advantage is taken of the fact that there isexcess heat available in the construction of the still, and in itsoperation. In the preheating operation, about vide each set of coilswith a reasonable excess of surface over and above that required toenable the transmission to the material being heated in the coils theamount of heat required to accomplish the heating operation for whichthe coil is designed. The excess of coil surface provided in each set ofcoils cannot operate to cause one set of coils to absorb more heat thanto superheat the steam to about theistill temperaturecan be absorbed.Similarly, in the coils provided for the preheating of the fatty acidfeed, only sumcient heat can be absorbed to heat the fatty acids toabout still temperature, and, as the coils used for the generation ofsteam are preferably located for absorbing heat after the vapors havepassed the superheating and proheating coils, any heat absorbed by thesesteamgenerating coils cannot deprive the others of heat. These lastcoils absorb more heat, and thus generate more steam than is necessaryfor the supply of superheated jet steam to the still, and this excesssteam can of course be used for other purposes. Similarly, the area ofthe surface of the cooling coils provided between the bell-deflector andthe outer shell of the still does not have to be carefully proportioned,as it is merely necessary to insure that these coils sufliciently coolthe outgoing vapors to insure the condensation of'all of the fattyacids.

The outletpipe through which the water vapor is conducted after thefatty acid vapors have been condensed and which leads to the vacuumdevices does not have to be as large as the other vapor passages in thestill, as the vapor which passes through this pipe has avolume which ismuch less than the volume of the vapors which pass, for example, throughthe separating zone. In the separating zone, and at the upper portionsof the primary cooling zone, the vapors consist of a mixture of fattyacid vapors and water vapor, and if, as in a typical case, the amount ofsuperheated jet steam used is about 10% of the Weight of the fatty acidsdistilled,

the ratio of the volumes of water vapor and fatty acid vapors is about 3to 2. Thus when the fatty acid vapors are removed, the volume of thevapors which must flow through the apparatus is reduced by abouttwo-fifths, and with the concomitant cooling of the water vapor, thevolume is still more reduced, so that the volume of vapor which passesthrough the outlet is much less than that which passes through theseparating zone.

In carrying out the process as described, and in apparatus as described,I find that it is possible to carry nut the distillation with pressuresin the still ranging from 3 mm. to 6 mm. of mercury, or even less. Theselow pressures within the still are made possible because the resistanceto flow of the vapors oifered in the various parts of the apparatus isextremely small, large passageways being provided for the vapors, sothat the difi'erence in pressure between the vapor space, for example,in the still and the portion of the outlet pipe adjacent to the-vacuumdevices may be as small as a fraction of a millimeter. Thus with avacuum device capable of reducing the pressure in the outlet pipe toabout 3 mm. of mercury, the amount of pressure required to force thevapors from the vapor space through the various parts of the apparatusand up to the vacuum devices may be as small as a fraction of amillimeter, with the result that the distillation itself is carried outwithin the apparatus and at a pressure of 4 mm. of mercury or less. Thislowered pressure which is maintained within the still enables the use ofconsiderably lower temperatures in the distillation, with consequentdecrease in the de-' composition of the fatty acids, particularly theunsaturated fatty acids which are always present in commercial fattyacids, and increases the yield of distilled acids and improves thequality of the distilled acids.

v The only source of outside or external heat which need be used incarrying out the process and in operating the apparatus is the highpressure steam supplied to the heating coils at the bottom of the still.The amount of heat which is required to be supplied by these heatingcoils is radically less than the amount of heat required to be suppliedtocarry out a similar distilling operation in such stills as haveheretofore been provided, being about 30% of the heat heretofore.

required, or even less. The only heat required to be supplied is theheat to vaporize the fatty acids at about the temperature at which theyare vaporized, in other words, the latent heat of vaporization of thefatty acids, and the small amount of heat which is lost by radiationfrom the lower portion of the still, that is, the portion of the stillbelow the vapor space. This radiation loss is only about one-fourth, orpossibly a little less. than one-fourth, of the radiation lossordinarily encountered in stills of similar capacity.

In similar distillation operations as heretofore carried out, it hasbeen necessary to preheat the fatty acids and to generate the steam andsuperheat the steam by outside sources of heat; the heat content of thevapors has never been made available for these purposes before. Theamount of heat which has heretofore been required for preheating and forgenerating steam and superheating it has been about twice the amount ofheat required to supply the latent heat of vaporization of the fattyacids or somewhat more, and as the radiation losses from such stills ashave heretofore been provided have been about four times the radiationloss from the still of the present invention, it is apparent that incarrying out the process of the present invention, the amount of heatwhich must be supplied to carry out the distillation is about one-third,or less, of the amount of heat which has heretofore been required. Thissubstantial saving in the amount of heat required, coupled with thegreater yield and improved quality of the distilled acids are advantageswhich flow from the present invention.

As an illustration of the heat economy which can be obtained by thepresent invention, the following comparison of the heat consumption of astill operated in accordance with the present invention, and a stillconstructed and operated in accordance with common practice, is given.This heat balance is based upon the assumption that both stills areoperating on the same material and are distilling it at equal rates, andthe further assumptions that the stills are operated at such a rate that2400 pounds of distillate per hour, from a feed containing 99% freefatty acids, are obtained; that the average still temperature is 428 F.;that the specific heat of the feed and fatty acids is 0.6; that thelatent heat of vaporization of the fatty acids is B. t. u. per pound;that thefatty acids are fed to the stills at 200 F.; that the distillateleaves the still at F.; that the water supplied is at 122 F.; and thatthe superheated jet steam used is 240 pounds per 1 hour, or 10% of theweight of the fatty acids distilled. It is also assumed that the stillconstructed and operated according to common practice is insulated inaccordance with accepted practice over its entire surface, over thegooseneck, and over the separator, and that the still operated inaccordance with the present invention is insulated over the-bottom andup the sides to a point slightly over the level of liquid within thestill. All of the assumptions made above are well within the range ofactual practice, and any variations in these assumptions will effect theresults but slightly provided theassumptions are properly applied toboth types of stills alike, with the actual advantages of operatingaccording to the present invention being taken into account.

Based upon these assumptions, the following table shows the heatrequired for the operation of a still constructed and operated as incommon The following table shows the amount of heat required foroperating a still adapted for use in carrying out the process of thisinvention and operating in accordance with the present invention anddistilling atthe same rate for a period of one hour.

It will be noted that in the second table, no heat input is required forgenerating the steam or for superheating it or for preheating the feed,because, as pointed out above, there is more heat available from thevapors than is required for these purposes. It might be'pointed out thatthe amount of steam required to carry out the distillation is somewhatless when the improved process and apparatus of the present inventionare used than has heretofore been required, and that less jet steam canbe used with equally eflicient distillation, largely because of the factthat the apparatus offers almost no resistance to flow of the vapors andallows the use of a smaller pressure differential between the vaporspace and the vacuum device, and a higher vacuum within the still.However, this decreased amount of steam which may be used in carryingout the process would not affect the heat balance givenabove, as thereis more than enough heat avail able to generate and superheat 10% ofsteam based upon the weight of the fatty acids, or even more. In anyevent, less'jet steam is required when operating in accordance with thepresent invention and the still may be operated with less jet steam thanother types of stills, while giving equivalent performance. Theresulting lesser amount of'water vapor produces an important economy andimprovement in vacuum in the operation of the vacuum device.

Where desired, the cooling space provided may be separated intovariouszones for the fractional condensation of the hot vapors, thuspermitting the fractionation of the distillate. Also, the invention inits broader aspects is advantageous for the dry distillation offattyacids.

Where the invention is used for the dry distillation of fatty acids, andno. supply of superheated jet steam is required, the heat given up bythe hot vapors in the cooling zone may be used to preheat the feed, andalso may be used to supply steam toother apparatus, or may be used forheating other liquids as desired. Nevertheless, the invention isparticularly applicable to the vacuum-steam distillation of fatty acids.For example, in the distillation of fatty acids from cocoanut oil, theuse of jet steam enables the distillation to be carried out at atemperature as much as 25 F. or more, lower than the temperaturerequired if the jet steam is not used, and simple dry distillation isused, and the drop in the temperature when distilling fatty acidsderived from 'tallow is even greater. Furthermore, the steam aids inbringing about intimate contact of the liquid being distilled with theheating coils and insures the intimate and effective contact of theliquid with the heating coils, thus greatly increasing the rapidity ofthe distillation.

I do not in this application claim the new apparatus described, as thisis claimed in my divisional application Serial No. 145,126, filed May27, 1937.

I claim:

1. The process of distilling fatty acids from a body of liquidundergoing distillation in the lower portion of a still provided withindirect heating means to supply the latent heat of vaporization whichcomprises vaporizing such fatty acids with the aid of indirect heat anda high vacuum, separating entrained unvolatilized material from theresulting hot vapors without substantially reducing their temperature,-and preheating the' fatty acid feed to substantially" the temperature ofthe still by subsequent indirect generally countercurrent contact withthe hot vapors freed from entrained and unvolatilized material, the hotvapors being brought from said body of liquid in the lower portion ofthe still into such contact with the feed before undergoing anysubstantial reduction in temperature below the temperature. of said bodyof boiling liquid.

2. The process of distilling fatty acids from a body of liquidundergoing distillation which comprises vaporizing such fatty acids withthe aid of heat, direct steam and a high vacuum, separating entrainedunvolatilized material from the resulting hot vapors withoutsubstantially reducing their temperature, and subsequently passing thehot vapors over cooling means in indirect heat exchange relationshiptherewith for condensation of fatty acid vapors, and to'generate saiddirect steam from water supplied to a portion of said cooling means andto heat the fatty acid feed and generated direct steam separately withheat recovered from said hot vapors to substantially the temperature ofthe still, the hot vapors being brought into contact with said coolingmeans before undergoing any substantial reduction in temperature, andcontacting said.

heated direct steam and said heated fatty acid feed within said body ofliquid undergoing distillation for the volatilization of fatty acids.

3. The process of claim 2, in which the hot vapors, after the removal ofentrained material, are brought successively into indirect generallycountercurrent contact with steam, fatty acid feed, and water, tosuperheat the steam and preheat the feed to substantially thetemperature of the still, and to generate said steam.

4. The process as in claim 2, in which all of the direct steam used forvolatilizing fatty acids is generated and brought to substantially stilltemperature by means of heat recovered and absorbed from the hot vaporsin. cooling and condensing therefrom distilled fatty acids.

5. The process of distilling fatty acids which comprises vaporizing suchfatty acids with the aid of heat and a high vacuum, separating entrainedunvolatilized material from the hot vapors by contacting all of suchvapors with hot deflecting surfaces without substantially reducing theirtemperature; and preheating the fatty acid feed to substantially thetemperature ofthe still by subsequent indirect generally countercurrentcontact with the hot vapors free from entrained unvolatilized material,the various steps of said process being performed in chambers providedwith in a single common outer shell.

6. The process of distilling fatty acids which comprises vaporizing suchfatty acids with the aid of heat, direct steam and a high vacuum,separating entrained unvolatilized material from the resulting vapors bycontacting all of such vapors with hot deflecting surfaces withoutsubstantially reducing their temperature, and passing the hot vaporsover cooling means in indirect heat-exchange relationship to generatesaid direct steam from water supplied to a portion of said cooling meansand to heat the fatty acid feed to substantially the temperature of thestill, and contacting within the still the steam so generated and theheated feed for the volatilization of fatty acids, the various steps ofsaid process being performed in zones provided Within a single commonouter shell.

7. The process of claim 6, in which the hot vapors, after the removal,of entrained material,

are brought successively into indirect generally countercurrent contactwith steam, fatty acid feed, and water, to superheat the steam andpreheat the feed to substantially the temperature of the still, and togenerate said steam.

8. The process of vacuum-steam distilling fatty acids which comprisesvaporizing such fatty acids while intimately contacting them with astream of water vapor, separating entrained andunvolatilized materialfrom the resulting hot vapors by contacting all of such vapors with hotdeflecting surfaces, passing the hot vapors over cooling means inindirect heatexchange relationship to generate and superheat steam andto preheat the fatty acid feed to substantially the temperature of thestill, and bringing the steam so superheated and in controlled amountinto intimate contact with the liquid fatty acids being distilled, thevarious steps of said process being performed in zones provided within asingle, common outer. shell.

9. The process as in claim 6, in which all of the direct steam used forvolatilizing fatty acids is generated and brought to substantially stilltemperature by means of heat recovered and absorbed from the hotvaporsin cooling and condensing therefrom distilled fatty acids.

10. .The process of distilling fatty acids which comprises vaporizingsuch fatty acids from a body of liquid undergoing distillation with theaid of heat and a high vacuum, separating entrained unvolatilizedmaterial from the resulting hot vapors by contacting them with hotdefleeting surfaces without substantially reducing their temperature,and passing the hot vapors in indirect heat exchange relationshipsuccessively and countercurrently with fatty acid feed and coolingwater,whereby the fatty acid vapors are condensed and the fatty acid feed isheatedlto substantially the temperature maintained within the still, andsteam is generated from said cooling water by said condensing fatty acidvapors, adding said heated feed to the liquid undergoing distillationand supplying additional heat thereto while at still temperature andpressure to provide the latent heat necessary to volatilize the fattyacids.

11. The process of vacuum-steam distilling fatty acids which comprisesmaintaining a body of fatty acids undergoing distillation at asubstantially uniform temperature, continuously supplying to the body offatty acids undergoing distilla tion, at substantially. the sametemperature, the latent heat necessary to convert said fatty acids intofatty acid vapors, contacting said fatty acids undergoing distillationwith a stream of water vapor in controlled amounts preheated tosubstantially the same temperature, the water vapor so used beinggenerated by indirect contact, in heat exchange relationship, of coolingwater and the hot fatty acid vapors by heat recovered from and absorbedfrom such fatty acid vapors in hot deflecting surfaces and subsequentlycondensing the fatty acid vapors thus freed from unvolatilized material,both the separation of entrained unvolatilized material and thesubsequent condensation of the fatty acid vapors being performed inzones provided within a single com mon outer shell.

13. The process of distilling fatty acids which comprises vaporizingsuch fatty acids from a body of liquid undergoing distillation with theaid of heat, direct steam and a high vacuum, separating entrainedunvolatilized material from the resulting hot vapors withoutsubstantially reducing their temperature or pressure, passing theresulting hot vapors before any substantial reduction in temperature inindirect contact, in heat-exchange relationship, with water, fatty acidfeed, and steam, whereby the said fatty acid vapors are condensed andsteam is generated, and the steam so generated, in controlled amounts,and the fatty acid feed are heated with heat recovered from said fattyacid vapors to substantially the temperature maintained within thestill, and after being so heated are brought into direct contact withone another within said body of liquid for the volatilization of fattyacids therefrom, the various steps of said process being performed inchambers provided within a single common outer shell.

v 14. In the distillation of fatty acids by volatilizing the fatty acidsfrom a body of liquid undergoing distillation with the aid of heat and avacuum with subsequent condensation of the volatilized fatty acids, thesteps of separating entrained unvolatilized material from the fattyacid' vapors rising from a body of fatty acids undergoing distillationwithout substantial drop in temperature or pressure or substantialcondensation of volatilized fatty acids and fractionally condensingfatty acid fractions having different boiling points by passing thevapors through chambers maintained at substantially uniform pressure andat progressively lower temperatures for the separation of fatty acidfractions having different boiling points, the various steps of saidprocess being performed in chambers. provided within a single commonouter shell.

15. The process as in claim 1, in which the fatty acids are vaporizedWhile contacting them with a controlled stream of superheated directsteam, and in which such steam is generated and superheated by indirectcontact of water and steam generated therefrom with the hot vapors.

MARTIN HILL ITTNER.

CERTIFICATE OF CCRRECTION.

Patent No. 2,202,007. May 28, 191 0.

MARTIN HILL ITTNERQ It is hereby certified that error appears in theprinted specification of the above numbered patent requiringcorreetioneus follows: Page 1 first column, line 58, for "in" read --to;page 6, first col umn, line 214., for

the word "nut" read --out page 7, first column, line l for "214.0" re ad214009; second column, line 65, elaim5, for "with in" rea d --within--;and that the said Letters Petent should be read with this correctiontherein thatthe same mey conform to the record of the case in the PatentOffice.

Signed and sealed this 50thday of July, A. D. 191m.

t Henry Van Arsdale, '(Seel) Acting Commissioner of Patents.

